Hive B has a wax moth problem - or they're unusually good at coping with it. I'm betting that it's a problem. I'll know when it's warm enough to have a look inside.
I have found 4 wax moth larvae on the removable floor of the hive. I've been keeping the floor clear of debris so I don't think they hatched on the floor, unless there is more debris that I can't see.
My expectation is that this colony is tolerant of wax moth. That's not a good thing. This colony is small and has superseded at least once. It hasn't shown any characteristics which are obviously good from my point of view. I'm not going to destroy it but I wouldn't be sad if the hive became available during swarming season.